The disclosure of the following priority application is incorporated herein by reference in its entirety: Japanese Patent Application No. 11-341844 filed Dec. 1, 1999.
1. Field of the Invention
This invention relates to a stage device and an exposure apparatus, and more particularly to a stage device provided with a plurality of stages and an exposure apparatus provided with the stage device.
2. Description of Related Art
Conventionally, various exposure apparatus are used to fabricate a semiconductor device (integrated circuit), a liquid crystal display device, or the like by a photolithographic process. Recently, as semiconductor devices have become highly integrated, reduction projection exposure apparatus such as a step-and-repeat type projection exposure apparatus (a so-called stepper) and a step-and-scan type scanning projection exposure apparatus (a so-called scanning-stepper), that improves upon the stepper, have been widely used.
These types of projection exposure apparatus are predominantly used for the production of semiconductor devices. Therefore, processing capability as to how many wafers can be exposure-processed within a predetermined time, that is, throughput needs to be improved.
The following shows the main processes performed in these types of projection exposure apparatus.
(a) First, a wafer loading process is performed that loads a wafer onto a wafer holder of a wafer (substrate) stage by using a wafer loader.
(b) Next, a search alignment process is performed that performs position detection of the wafer by a search alignment mechanism. Specifically, the search alignment process is performed by, for example, using the image of the wafer as a reference or by detecting a search alignment mark on the wafer.
(c) Subsequently, a fine alignment process is performed that accurately obtains the position of each shot region on the wafer (each shot region corresponds to an area where a circuit pattern will be formed). This fine alignment process typically uses an EGA (Enhanced-Global-Alignment) method. In this method, arrangement data for all shot regions on the entire wafer can be obtained (see U.S. Pat. No. 4,780,617) by selecting a plurality of sample shot regions on the wafer, measuring the position of an alignment mark (wafer mark) arranged in the sample shots, and by performing statistical calculation by a so-called least squares method or the like based on this measurement result and a designed value of shot arrangement. Then, a coordinate position of each shot region can be obtained with high throughput and with relatively high accuracy.
(d) Next, an exposure process is performed in which an image of a pattern of a reticle (mask) is transferred onto the wafer (substrate) via a projection optical system as each shot region on the wafer is sequentially positioned at an exposure position based on a base alignment amount that was measured in advance and a coordinate position of each shot region obtained by the above-mentioned EGA method or the like.
(e) Next, a wafer unloading process is performed that unloads the wafer that has been exposure-processed from the wafer stage by using a wafer unloader. This wafer unloading process is simultaneously performed with the above-mentioned (a) wafer loading process for the next wafer to be exposure-processed. That is, a wafer replacement process is constituted by steps (a) and (e).
Thus, in a conventional projection exposure apparatus, three significant operations, such as: (1) wafer replacement; (2) alignment (search alignment, fine alignment); (3) exposure; and (4) wafer replacement, or the like, are repeated by using one wafer stage.
Even if some of the plurality of operations within the above-mentioned three operations, that is, wafer replacement, alignment, and exposure operation, can be performed simultaneously, throughput can be improved compared to the case when these operations are sequentially performed. Exposure of a wafer is not performed during wafer replacement and alignment, and thus in order to improve shortening of process time, that is, throughput, for example, a method can be considered that simultaneously independently controls a first stage in which wafer replacement and alignment are performed and a second stage in which exposure is performed.
With respect to this concept, for example, International Publication No. WO98/40791 discloses a stage device (positioning device) that independently drives two stages in parallel in a two-dimensional X-Y plane. This device provides a pair of driving mechanisms that are symmetrically arranged. Each driving mechanism has a stationary member of an X driving linear motor, opposite ends of which are attached to a respective one of two moving elements of a Y-axis linear motor of that driving mechanism. The moving elements of each Y-driving linear motor drive its stage in the Y-axis direction by a driving force of this Y driving linear motor. The stage device also has rigid connection mechanisms (coupling mechanisms) that couple a side of a stage (object holder) that faces the moving member of the X driving linear motor to that moving member. Thus, the two stages are coupled to the respective driving mechanisms by the respective connection mechanisms.
However, in the positioning device described in the above-mentioned WO98/40791, a rigid connection mechanism is used to couple respective stages to respective driving mechanisms. This rigid connection mechanism includes movable parts that are moved along with the stages, and therefore the weight of the movable parts becomes heavy. As a result, positioning control is not sufficiently assured with respect to the stages. Furthermore, in this positioning device, as described above, a rigid connection mechanism is used, and therefore a shock force generated during connection (during coupling) may cause a positional shift of a semiconductor substrate (wafer) on the stage. Additionally, as clarified from FIG. 2 or the like of the above-mentioned International Publication, a point of application of thrust of the stages is displaced from the center of gravity, so that rotational moment is generated.
This invention has been made in view of the above circumstances. One object of this invention is to provide a stage device that prevents a shock force from acting on a movable body when the movable body is positioned with respect to two stationary side members and that prevents an object that is to be mounted on the movable body from being positionally shifted.
Another object of this invention is to provide a stage device that can prevent a shock force from acting on the stages when the two stages are replaced and can simultaneously separately process objects mounted on the stages.
Another object of this invention is to provide an exposure apparatus that improves the ability to control the position of a substrate on a stage and simultaneously improves throughput.
The stage device according to one aspect of the invention includes a first stationary member, a second stationary member, a moving member and positioning devices. The first stationary member extends in a first direction. The second stationary member extends in the first direction and is spaced apart from the first stationary member in a second direction perpendicular to the first direction. The moving member can cooperate with the first stationary member and with the second stationary member. The positioning devices selectively position the moving member into cooperation with one of the first and second stationary members without physically contacting the moving member with the first and second stationary members.
In this specification, xe2x80x9ccooperationxe2x80x9d means any type of mutual interaction, for example, electromagnetic mutual interaction (including both electromagnetic mutual interaction and magnetic mutual interaction) that is performed between a stationary member and a moving member so that a driving force (thrust) that relatively drives the stationary member and the moving member relative to each other is generated. Furthermore, in this specification, a xe2x80x9cfirst directionxe2x80x9d and a xe2x80x9csecond directionxe2x80x9d have the same meaning as a first-axis direction and a second-axis direction. Therefore, when these words are used in relation to an operation, movement from one side to the other side along a first axis (e.g., Y axis) and along a second axis (e.g., X axis), as well as movement in the opposite direction, are included.
According to this aspect of the invention, the moving member can be selectively positioned into cooperation non-contactingly with one of the first stationary member and the second stationary member. Because of this, when positioning the moving member into cooperation with the stationary member, unlike in the case of the above-mentioned rigid connection mechanism, a shock force does not act on the moving member. Accordingly, this can prevent an object mounted on the moving member from having a positional shift.
In accordance with another aspect of the invention, a stage device provided with a moving member that can move within a two-dimensional plane having a first direction and a second direction perpendicular to the first direction includes a first stationary member and a second stationary member. The first stationary member extends in the first direction and is supported at a first position in a third direction that is perpendicular to the two-dimensional plane. The second stationary member extends in the first direction and is supported at a second position in the third direction, different from the first position. The moving member has a first part that can cooperate with the first stationary member, and a second part that can cooperate with the second stationary member.
In this specification, a xe2x80x9cthird directionxe2x80x9d has a meaning that is the same as a third-axis direction. In the case of using a xe2x80x9cthird directionxe2x80x9d in relation to an operation, movement from one side to the other side of a third axis (e.g., Z axis) and movement in the opposite direction are included.
According to this aspect of the invention, the first stationary member is supported at the first position in the third direction, the second stationary member is supported at the second position in the third direction, and the moving member has the first part that can cooperate with the first stationary member and the second part that can cooperate with the second stationary member. Because of this, by moving the moving member toward the first stationary member, the moving member can be non-contactingly positioned at a position in which the first part of the moving member can cooperate with the first stationary member. Additionally, by moving the moving member toward the second stationary member, the moving member can be non-contactingly positioned at a position in which the second part of the moving member can cooperate with the second stationary member. Thus, the moving member can be non-contactingly positioned at a position in which cooperation can be established with the first and second stationary members. Because of this, a shock force does not occur, which adversely affects the moving member, unlike in the case of the above-mentioned rigid connection mechanism. Therefore, generation of a positional shift to an object mounted on the moving member can be prevented.
In this case, as described above, while the moving member cooperates with one of the first stationary member and the second stationary member, driving devices can also be provided that can drive the moving member and one of the stationary members in the second direction.
A stage device according to another aspect of the invention includes a first stationary side member, a second stationary side member, a first stage, a second stage and replacement devices. The first stationary side member includes a first stationary member that extends in a first direction. The second stationary side member includes a second stationary member that extends in the first direction and is spaced from the first stationary member in a second direction perpendicular to the first direction. The first stage can cooperate with the first stationary member and with the second stationary member, and has a first moving member that can receive a thrust in the first direction when it is in cooperation with either the first stationary member or the second stationary member. The second stage can cooperate with the first stationary member and with the second stationary member, and has a second moving member that can receive a thrust in the first direction when it is in cooperation with either the first stationary member or with the second stationary member. The replacement devices can non-contactingly replace the first and second stages with respect to the first and second stationary side members.
Because the replacement devices can non-contactingly replace the first and second stages with respect to the first and second stationary side members, during the replacement, a shock force does not affect the respective stages, unlike in the case of the above-mentioned rigid connection mechanism. Thus, generation of a positional shift in an object (e.g., a substrate) mounted on the respective stages can be prevented. Furthermore, the first stage has a first moving member that can cooperate with the first stationary member or with the second stationary member and that receives a thrust in the first direction during the cooperation, and the second stage has a second moving member that can cooperate with the first stationary member or with the second stationary member and that receives a thrust in the first direction during the cooperation. Therefore, both stages can be independently driven simultaneously at least in the first direction. Accordingly, separate processing operations can be simultaneously performed for the object mounted on the respective stages.
In addition, the replacement devices can also be provided with an adjustment device that adjusts an interval in the second direction between the first stationary side member and the first moving member. In this case, the interval in the second direction between the first stationary side member and the first moving member can be adjusted by the adjustment device, so that the first moving member can be non-contactingly supported in the second direction for the first stationary side member so that this interval has an appropriate dimension and is maintained constant. At the same time, the first moving member can be substantially accurately guided non-contactingly in the first direction along with the first stationary side member. In this case, the replacement devices can also be provided with an adjustment device that adjusts the interval in the second direction between the first moving member and the second stationary side member, and adjustment devices that respectively adjust the interval in the second direction between the second moving member and respective ones of the first and second stationary side members.
According to another aspect of the invention, it is preferable that a plurality of the adjustment devices are arranged in the first direction. In this case, by adjusting the interval in the second direction between the first moving member and the first stationary side member at a plurality of points at different positions in the first direction, axial rotation about the third direction of the first stage can be adjusted.
Various different structures can be used as adjustment devices in the above aspects of the invention. For example, the adjustment devices can have an electromagnet arranged in the first moving member and magnetic body members arranged in the first stationary side member. In this case, the interval in the second direction between the first moving member and the first stationary side member can be adjusted by adjusting a magnetic force (magnetic attraction for the magnetic body member) that is electromagnetically generated.
It is preferable that the point of application of thrust in the first direction for the first and second stages is set at a position that passes through the center of gravity of the respective stages. In this case, rotation of the first stage when the first stage is driven in the first direction by cooperation between the first moving member and the first or second stationary member can be prevented, and rotation of the second stage when the second stage is driven in the first direction by cooperation between the first or second stationary member and the second moving member can be prevented.
According to another aspect of the invention, the stage device having a first stage and a second stage that can be independently moved in a two-dimensional plane having a first direction and a second direction perpendicular to the first direction includes a first stationary member and a second stationary member. The first stationary member extends in the first direction and is supported at a first position in a third direction that is perpendicular to the two-dimensional plane. The second stationary member extends in the first direction and is supported at a second position different from the first position in the third direction. A first stage includes a first moving member having a first part that can cooperate with the first stationary member, and a second part that can cooperate with the second stationary member. A second stage includes a second moving member having a first part that can cooperate with the first stationary member and a second part that can cooperate with the second stationary member.